<?php
namespace App\CMS\Pipeline;

use App\CMS\Contracts\Content\DisplayPipeline\Pipeline;
use App\CMS\Contracts\Content\DisplayPipeline\Process;
use App\CMS\Pipeline\Exceptions\InvalidProcessType;
use App\Http\Controllers\Controller;
use App\Models\Content\Content;

class DisplayPipeline implements Pipeline
{
    protected $processes = [];
    protected $beforeStart = null;
    protected $beforeRender = null;

    /**
     * Add new process into pipeline
     *
     * @param $process
     *
     * @return void
     * @throws InvalidProcessType
     */
    function add($process)
    {
        $this->checkValidProcess($process);

        $this->processes[] = $process;
    }

    /**
     * check if given classname implements Process interface
     *
     * @param $classname
     *
     * @throws InvalidProcessType
     */
    protected function checkValidProcess($classname)
    {
        if (!in_array(Process::class, class_implements($classname))) {
            throw new InvalidProcessType($classname);
        }
    }

    /**
     * @param null $beforeStart
     */
    public function setBeforeStart($beforeStart)
    {
        $this->checkValidProcess($beforeStart);

        if (!is_null($this->beforeStart)) {
            array_unshift($this->processes, $this->beforeStart);
        }

        $this->beforeStart = $beforeStart;
    }

    /**
     * @param null $beforeRender
     */
    public function setBeforeRender($beforeRender)
    {
        $this->checkValidProcess($beforeRender);

        if (!is_null($this->beforeRender)) {
            array_push($this->processes, $this->beforeRender);
        }

        $this->beforeRender = $beforeRender;
    }

    /**
     * Run pipeline
     *
     * @param Content $page
     *
     * @return Content
     */
    function run(Content $page)
    {
        $this->runBeforeStart($page);

        foreach ($this->processes as $process) {
            /**
             * @var $run Process
             */
            $run = new $process;
            $run->handle($page);
        }

        $this->runBeforeRender($page);

        return $page;
    }

    private function runBeforeStart($page)
    {
        if (!is_null($this->beforeStart)) {
            $process = new $this->beforeStart;
            $process->handle($page);
        }
    }

    private function runBeforeRender($page)
    {
        if (!is_null($this->beforeRender)) {
            $process = new $this->beforeRender;
            $process->handle($page);
        }
    }
}